Intro to the LoW

7/31/2019 Intro to the LoW

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T h e L a k e o f t h e W o o d sT h e L a k e o f t h e W o o d s

**NOTE: Presentation slides are annotated: place cursor over com**NOTE: Presentation slides are annotated: place cursor over comment bubble to toggle on or off **ment bubble to toggle on or off **


2/17

Home to species that are absent/rare in the rest of Ontario, Canada, and the world.

White-tailed Jack Rabbit

Franklins Squirrel American White Pelican Piping Plover

Green-faced clubtail dragonfly

Some examples include:


3/17

LoW remnant of glacial Lake Agassiz- largest lake in N. America

during the last deglaciation

Mud Portage petroglyphs: evidence for 1st inhabitants, late Paleoor Plano people ~9,300 yr BP

~2,200 yr BP: arrival of Early Woodland people including

the Laurel people

harvested, cooked & stored wild rice

~AD 1688 first European to sight LoW: Jacques De Noyen

18th & 19th centuries: LoW a hub for fur traders and missionaries

1850: Gold discovered

Source: Windows to the Universe, at http://www.windows.ucar.edu/

Source: Robertson and McCracken 2003


Lake of the Woods

Lake Agassiz
http://www.windows.ucar.edu/http://www.windows.ucar.edu/


4/17

~1877: Canadian Pacific Railway in the region

Late 1800s early 1900s- Rat Portage (now Kenora)

major lumber industry centre

1872: 1st steamship on the LoW

~1887 to ~1900: dams built at northern outlets to the Winnipeg R. average water level rises by ~2m

~1890-1900: Sturgeon fishing frenzy: caviar

within a decade unregulated sturgeon fishery went fromboom (350,000 kilos/year) to bust

Today LoW is still a major tourist attraction




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6/17

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0510

km

OntarioManitob

a

Minnesota

Kenora

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Man

itoba

Ontario

Minnesota

One of Ontarios largest inland lakes: ~385,000 ha (excluding Shoal Lake)


7/17

Numerous depositional basins Hundreds of inlets and bays >14,500 islands


8/17

Large drainage basin 69,750 km2

Low lake to drainage basin area ratio Highly susceptible to activities in its catchment

Map by Gartner Lee Ltd.


9/17

BigTraverseBay

Kenora

Modified from Robertson & McCracken 2003

RainyRiver

Rainy Riverprovides ~70% of

inflow through LoW

Water flowsnorthward through

main channel

Major outlet isWinnipeg R. in the

north


10/17

Site

PP-12

PP-13

PP-14PP

-6

PP-15PP

-5PP

-4PP

-7PP

-3PP

-2PP

-8PP

-1PP

-9

PP-11

PP-18

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PP-16

Totalphosphorus

(

gL-1)

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Whitefish Bay

PP-1

Bigstone Bay

Results of this initiative published inJ. Great Lakes Res. Pla et al. 200531:253-266

Long-term monitoring has shown LoW experiences significant inter-annual andspatial variability in nutrients with highest concentrations in late summer

Strong TP gradient tracks direction of flow from the Rainy River (Pla et al. 2005) Higher TP concentrations along main channel and in the south end

Summer total phosphorus (TP) measurements

Low Medium High


11/17

August 31st

July 18th

June 19th

(Terra MODIS images G. McCullough, U. of Winnipeg)

Typically blooms occur in mid summer in the south end of the lakeand in late summer to early fall, at the north end.


12/17

There is a perception that water quality in the LoW has deteriorated inrecent years due to a reported increase in the frequency and intensity ofcyanobacterial algal blooms.

Interest in determining if this is true

Interest in understanding why


13/17

Total phosphorus (TP) important, limiting nutrient for algal growth Much interest in determining whether TP has changed historically

Has TP been historically high in LoW?

Has TP increased recently?

Historical documents back to early 1820s describe algal blooms


14/17

The islands were numerous and crowded, the water shoaland foul, frequently with a green scum of vegetable matter

- Major Joseph Delafield, July 30th, 1823

the water became tinged with green, derived from aminute vegetable growth

- S. J. Dawson, Summer 1857

deposits of green vegetable matter in thelakes bays during the summer.

- objection to a proposal to use LOW to supply clean

water to Winnipeg 1883


15/17

Although historical reports give important insights into past environmentalconditions, they cannot provide us with answers to key lake managementquestions


16/17

1) What is the natural or baseline condition of the lake?

2) Has the water quality changed since pre-development (orpre-industrial) times?

3) If so, when did these changes occur?

4) What is the direction and magnitude of this change?

5) What are the possible reasons for this change?

Answers to these questions can provide evidence for possible mechanisms

underlying these changes.


17/17

Our research on the Lake of the Woods examines the remains of biologicalassemblages preserved in lake sediments as a key to past environmental conditions.

To learn more aboutPaleolimnologyand our work on the Lake of the Woods,

visit our slideshow Spotlight on Paleolimnology featured on our HomePage.

Some examples of remains preserved in lake sediments:

Diatoms: siliceous algae Chironomids: non-biting midges Cladocerans: water fleas

Documents

Intro to the LoW